Scooby,
The diameter would okay, Uberti also made the 1858 Conversion Cylinder & Frame larger then the Cap & Ball. Probably so you couldn't go purchase a cartridge cylinder & install it on your Cap & Ball Revolver, (liability & lawyers). If the 45 Schofield/Colt fits so will a 44 Colt, it's smaller. The issue is the ratchet. Original 1851 & 1860's had the teeth centered on the chambers, the factory conversion moved the teeth to between the chambers, requiring a 2 stage hand to index the ratchet a little further to line up the chamber with bore. Are your ratchet teeth centered on the Chamber or set between them? This could also be the reason they made them larger, no longer requiring a two stage hand. I know there are guys out there who have them, I just wonder where they came from. Probably custom builds beyond my budget, still fun to dream.